Evaporative coolers have been provided with various means for holding evaporative cooler pad assemblies and louver grills and various means for removeably retaining louver grills and for providing access to the evaporative cooler pad assemblies. However, many prior art evaporative cooler construction features have failed to provide simple access doors which properly expose upper portions of evaporative cooler pad assemblies and also properly lock louver grills in place at their upper edges. The prior art evaporative cooler structures have been somewhat difficult to service in many ways due to difficult access to the water trough structure and the upper portions of evaporative cooler pad assemblies to check for even flow of water into the troughs for efficient wetting of the pads in the pad assemblies and further, the prior art has afforded relatively difficult to to operate mechanism for retaining louver grills relative to the evaporative cooler frame and relative to respective evaporative cooler pad assemblies. Furthermore, the prior art has provided a great variety of frame and structural features which include sump pans, corner posts and top cover pans or top structures and these various mechanical features have heretofore been relatively expensive to produce and assemble.